The present invention relates generally to medical devices and particularly to a template for delivering annuloplasty repair segments or rings especially for use in minimally-invasive surgeries.
Prosthetic annuloplasty rings are used to repair or reconstruct damaged or diseased heart valve annuluses. In vertebrate animals, the heart is a hollow muscular organ having four pumping chambers: the left and right atria and the left and right ventricles, each provided with its own one-way valve. The natural heart valves are identified as the aortic, mitral (or bicuspid), tricuspid and pulmonary valves. The valves of the heart separate chambers therein, and are each mounted in an annulus therebetween. The annuluses comprise dense fibrous rings attached either directly or indirectly to the atrial and ventricular muscle fibers.
Heart valve disease is a widespread condition in which one or more of the valves of the heart fails to function properly. Diseased heart valves may be categorized as either stenotic, wherein the valve does not open sufficiently to allow adequate forward flow of blood through the valve, and/or incompetent, wherein the valve does not close completely, causing excessive backward flow of blood through the valve when the valve is closed. Valve disease can be severely debilitating and even fatal if left untreated, particularly if the diseased valve is the mitral valve (between the left atrium and left ventricle) or the aortic valve (between the left ventricle and the aorta). According to recent estimates, more than 80,000 patients are diagnosed with aortic or mitral valve disease in U.S. hospitals each year.
Various surgical techniques may be used to repair a diseased or damaged valve. In a valve replacement operation, the damaged leaflets are excised and the annulus sculpted to receive a replacement valve. Another less drastic method for treating defective valves is through repair or reconstruction, which is typically used on minimally calcified valves. One repair technique which has been shown to be effective in treating incompetence, particularly of the mitral and tricuspid valves, is annuloplasty, in which the effective size of the valve annulus is contracted by attaching a prosthetic annuloplasty repair segment or ring to an interior wall of the heart around the valve annulus. The annuloplasty ring is designed to support the functional changes that occur during the cardiac cycle: maintaining coaptation and valve integrity in systole while permitting good hemodynamics in diastole. Where contracting or stabilizing the valve annulus might be desirable, annuloplasty rings may also be utilized in combination with other repair techniques such as quadrangular resection, commissurotomy, shortening mitral or tricuspid valve chordae tendonae, reattachment of severed mitral or tricuspid valve chordae tendonae or papillary muscle tissue, and decalcification of the valve leaflets or annulus. The annuloplasty ring typically comprises an inner substrate of a metal such as stainless or titanium, or a flexible material such as silicone rubber or Dacron cordage, covered with a biocompatible fabric or cloth to allow the ring to be sutured to the heart tissue. Annuloplasty rings may be stiff or flexible, may be split or continuous, and may have a variety of shapes, including circular, D-shaped, C-shaped, or kidney-shaped. Examples are seen in U.S. Pat. Nos. 4,917,698, 5,061,277, 5,290,300, 5,350,420, 5,104,407, 5,064,431, 5,201,880, and 5,041,130, which are incorporated herein by reference.
Using current techniques, most valve repair procedures require a gross thoracotomy, usually in the form of a median sternotomy, to gain access into the patient""s thoracic cavity. A saw or other cutting instrument is used to cut the sternum longitudinally, allowing two opposing halves of the anterior or ventral portion of the rib cage to be spread apart. A large opening into the thoracic cavity is thus created, through which the surgical team may directly visualize and operate upon the heart and other thoracic contents. Alternatively, a thoracotomy may be performed on a lateral side of the chest, wherein a large incision is made generally parallel to the ribs, and the ribs are spread apart and/or removed in the region of the incision to create a large enough opening to facilitate the surgery. Using such open-chest techniques, the large opening provided by a median sternotomy or right thoracotomy enables the surgeon to see the affected valve directly, and to position his or her hands within the thoracic cavity in close proximity to the exterior of the heart for cannulation of the aorta and/or coronary arteries to induce cardioplegia, manipulation of surgical instruments, removal of excised tissue, and introduction of an annuloplasty ring or a replacement valve through the atriotomy for attachment within the heart. However, these invasive, open-chest procedures produce a high degree of trauma, a significant risk of complications, an extended hospital stay, and a painful recovery period for the patient. Moreover, while heart valve surgery produces beneficial results for many patients, numerous others who might benefit from such surgery are unable or unwilling to undergo the trauma and risks of current techniques.
Naturally, surgical patients desire operations be performed with the least amount of intrusion into the body. Recently, a great amount of research has been done to reduce the trauma and risk associated with conventional open heart valve replacement surgery. In particular, the field of minimally invasive surgery (MIS) has exploded since the early to mid-1990s, with devices now being proposed to enable valve replacements without opening the chest cavity. Such proposed MIS heart valve repair or replacement surgeries still requires bypass, but the procedures are accomplished via elongated tubes or cannulas introduced through one or more small access incisions in the thorax, with the help of endoscopes and other such visualization techniques. Such minimally invasive procedures usually provide speedier recovery for the patient with less pain and bodily trauma, thereby reducing the medical costs and the overall disruption to the life of the patient. A minimally invasive approach also usually results in a smaller incision and, therefore, less scarring, which is an aesthetic advantage attractive to most patients. The use of a minimally invasive approach, however, introduces new complexities to surgery thus placing a greater burden on the operating surgeon. Most notably, minimally invasive approaches drastically reduce the size of the surgical field available to the surgeon for the manipulation of tissue and for the introduction of necessary surgical instruments, such as cutting devices, clamps, prosthetic holders, and so on. These complexities are especially acute in connection with heart surgery. Unlike common heart surgeries performed using a full medial sternotomy, minimally invasive heart surgery offers a surgical field that may be only as large as a resected intercostal space or a transversely cut and retracted sternum. Consequently, the introduction of tools, such as prosthetic sizing elements, valve holders, annuloplasty ring holders, and other such devices, becomes a great deal more complicated.
The majority of instruments currently available to surgeons for performing minimally invasive surgeries are devices designed for use in far less restrictive surgical fields. That is, the existing instruments have characteristics which are not conducive for use in restrictive surgical fields. For example, in heart surgery, the majority of implements available to hold or retain various heart devices or tools (e.g., heart valves and annuloplasty rings) in a minimally invasive procedure either are too short to enable easy introduction of prostheses to the target site and/or have shafts which lack the necessary malleability or flexibility to enable proper orientation of the prostheses at the distal end of the shaft. Examples of such prior art devices are disclosed in U.S. Pat. No. 4,679,556 to Lubock et al.; U.S. Pat. No. 5,531,785 to Love et al.; U.S. Pat. No. 5,360,014 to Sauter et al.; U.S. Pat. No. 5,403,305 to Sauter et al.; U.S. Pat. No. 5,476,510 to Eberhardt et al.; U.S. Pat. No. 5,489,296 to Love et al.; and U.S. Pat. No. 5,560,487 to Starr.
One technique proposed for minimally invasive annuloplasty repair, disclosed in U.S. Pat. No. 5,972,030, involves a delivery handle that enables the annuloplasty ring carried thereon to pivot 90xc2x0. That is, the ring mounted on a rigid template is aligned along the handle axis during insertion through an access port, and is then rotated from the proximal end of the handle to a perpendicular implantation orientation. This technique relies on an oval-shaped access port to pass the ring and template into the chest cavity, and thus additional special implements are required.
What is needed, therefore, are devices and methods for carrying out heart valve repair that reduce the trauma, risks, recovery time and pain that accompany current techniques. The devices and methods should facilitate surgical intervention without the need for a gross thoracotomy. In particular, the devices and methods should allow for the introduction of surgical instruments to facilitate heart valve repair. The devices and methods should enable the implantation of annuloplasty repair segments or rings of various shape, size, and stiffness without the need for excessive additional implements.
The present invention provides a holder for an annuloplasty repair segment, comprising an elongate template adapted to attach to the repair segment. The template is adapted to pass in a generally linear shape through a tube, and is convertible from the generally linear shape to a curved shape. In one embodiment, the template is flexible, and may be biased toward the curved shape. The curved shape may be two- or three-dimensional. A deflection mechanism may be provided for actively converting the template between the linear shape and the curved shape. In one embodiment, the holder further includes an anchor mandrel to which the template is releasably attached, and a tether maintaining a connection between the template and the anchor mandrel when released.
In a further embodiment, a combined annuloplasty repair segment and holder is provided, where the holder has a template with a generally linear shape in at least one position and is adapted to undergo a shape change along its length. The repair segment attaches to the template and is configured to assume the changed shape of template. The template may be capable of a temperature-induced shape change between the linear shape and changed shape. In one embodiment, template is flexible, but unbiased from the linear shape, and a holder further includes a biasing member adapted to insert within the template so as to bias the template toward the curved shape. A handle may be attached to the template for manipulating the template to position the repair segment into proximity with a valve annulus. The template may be provided with suture location markers to facilitate suture alignment with anatomical landmarks.
In a further embodiment, an annuloplasty repair segment delivery system of the present invention includes a delivery sheath, an anchor mandrel, and an elongate template. The anchor mandrel is slidably disposed within the sheath near a distal end thereof, yet is restrained from exiting the sheath. The template is adapted to attach to a flexible annuloplasty repair segment and is releasably attached to the anchor mandrel. The template is convertible from a generally linear shape within the sheath, to a curved shape when ejected from the distal end of the sheath. The system further may include a tether connecting the template and anchor mandrel when released. In one embodiment, the template is biased toward the changed shape, which may be a two- three-dimensional curve. The template may include a handle portion and a forming portion, the forming portion being biased into a curved shape and being attached to the repair segment so that the segment assumes the curved shape. In one embodiment, the forming portion inserts within the segment.
In still another aspect of the present invention, a method of implanting an annuloplasty repair segment in a heart valve annulus comprises the steps of:
1. providing a holder having a flexible template adapted to attach to an annuloplasty repair segment, the template being convertible from a generally linear shape to a curved shape;
2. attaching an annuloplasty repair segment to the flexible template;
3. delivering the repair segment attached to the template to a heart valve annulus;
4. causing the template and repair segment to simultaneously undergo a shape change; and
5. attaching the annuloplasty repair segment to the annulus.
The method may also include a step of delivering the annuloplasty repair segment attached to the template through a minimally-invasive tube. The minimally invasive tube may be inserted through an access incision in the chest wall, or through an access incision in the peripheral vasculature and through vascular system, both into proximity within the annulus. The method may include releasing the template from the end of the tube, and maintaining a tether connection between the template and an anchor mandrel from within the tube.
A further understanding of the nature and advantages of the invention will become apparent by reference to the remaining portions of the specification and drawings.